According to Corrinne Yu's LinkedIn page, the Halo 4 Principal Engine Programmer has left Microsoft's Halo team, and joined the developer of The Last of Us and Uncharted, Naughty Dog.

What makes this more interesting, is that she is really leaving Microsoft, for its key rival in the console space, Sony. Yu worked as the Principal Engine Programmer with 343 Industries for five years, and before that she worked at Gearbox Software as its Director of Technology. Yu has some experience under her belt, including Halo 4, Borderlands and I don't want to mention it, but I have to: Aliens: Colonial Marines.